Transmission controls



Oct. 17, 1961 G. E. FLINN TRANSMISSION coNTRoLs 6 Sheets-Sheet 1 Filed May 25. 1956 fraz/enfer.' 6160719@ Zmm Oct. 17, 1961 G. E. FLINN 3,004,446

TRANSMISSION CONTROLS Filed May 25. 1956 6 Sheets-Sheet 2 /7 f7.4 FEA/P PUMP j /0/ deoflge fffvlczm ,zy

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TRANSMISSION coNTRoLs Filed May 25, 1956 6 Sheets-Sheet 4 Oct. 17, 1961 n G. E. FLINN I 3,004,446

TRANSMISSION CONTROLS Filed May 25, 195e e shets-sheet s Oct. v17, 1961 Filed May 25, 1956 G. E. FLINN 3,004,446

TRANSMISSION CONTROLS 6 Sheets-Sheet 6 JMJ- @d/ a@ drive.

'which may be termed a front servo release control My invention relates to transmissions for automotive vehicles and more particularly to hydraulic controlling mechanism for such transmissions.

Hydraulically controlled transmissions of the general type contemplated are now in common commercial usage. One of these provides three speeds in forward drive, all of which include a hydraulic torque converter that multiplies torque. This transmission is under the control of a manually operated selector element having a drive range position and a low range position. In the drive range, the transmission starts the vehicle in intermediate speed drive, and, subsequently, theV hydraulic controlling mechanism shifts or changes the transmission automatically into high speed drive. In the low range, the transmission remains in its low speed drive.

It is an object of the present invention to provide improved controls for such a transmission having a selector element with two drive range positions, in one of `which the transmission will begin operating in intermediate speed drive and will subsequently upshift to direct drive and in the other of which the transmission will begin to drive the vehicle in low speed drive and will subsequently, automatically and sequentially upshift the transmission to intermediate speed drive and then to high speed drive.

More particularly, it is an object to have a range control valve in the hydraulic controls which is connected with an automatic shift valve controlling shifts between low and intermediate speed drive, the range control valve vat times applying a driven shaft governor responsive pressure on the shift valve andat other times applying a relatively high fluid pressure on the shift valve holding it in its upshifted position, so that the operation in the first above-mentioned drive range may be accomplished.

In a transmission of the type mentioned, both the low and intermediate speed drives are completed by means of vfriction brakes. It is an object in connection with such a transmission to provide an improved mechanism for controlling the engagement and disengagement of these brakes so that changes between the low and intermediate speed drives may be accomplished without shock. More particularly, it is an object to provide improved valving under the control of the vehicle accelerator which provides a restriction in series with actuating servo motors for both brakes for all upshifts but by-passes the restriction with respect to one of the servo motors for downshifts from intermediate speed drive to low speed drive when the accelerator is in a closed throttle position.

An automatic 2 3 shift valve is provided in my improved controls in addition to the 1 2 shift valve abovementioned, the 2 3 shift valve being effective for providing an automatic shift to high speed drive from intermediate speed .drive after the 1 2 shift valve has been effective to cause a shift from low to intermediate speed It is an object also to provide a shuttle valve valve for at times connecting the 1 2 shift valve with .the servo motor for the intermediate speed brake and at other times connecting the 2 3 shift valve with this brake so that both of the shift valves may at times each be effective for controlling actuation of the brake.

It is also an object in connection with the 1 2 and 2 3 shift valves to provide grooves with unbalanced hysteresis areas in -these valves tending to hold each of them in either a downshiftedor upshifted position, more particulan-ly, the hysteresis area on the 1 2 shift valve holding this valve in its downshifted position and the hysteresis area on the 2 3 shift valve holding this valve in its upshifted position. It is contemplated that each of these valves shall transmit fluid pressure to the various power train completing friction engaging devices through the respective grooves and that the pressure transmitted shall increase in accordance with increases in engine throttle opening. Therefore, with the valves being in their downshifted positions, the hysteresis effect will increase with increases in throttle opening on the 1 2 shift valve but will not on the 2 3 shift valve, and it is accordingly an object of my invention to provide this throttle valve varied pressure effective also on the 2-3 shift valve tending to hold it in its downshifted position for maintaining the spacing between the shift points of these two valves approximately the same regardless of variations in the throttle controlled pressure.

The invention herein disclosed constitutes improvements on the transmission controls shown in the application of Robert W. Wayrnan, SN. 166,136, filed June 5, 1950, the application of Robert W. Wayman, S.N. 249,- 296, filed October 2, 1961, now Patent No. 2,770,148, my copending application (Borg-Warner Corporation S.N. 563,513, tiled February 6, 1956, now Patent No. 2,893,261, and the copending application of which I and William V. Harrison are the applicants, S.N. 462,300, tiled October 14, 1954, now Patent No. 2,938,403.

The invention consists of the novel constructions, arrangements and devices to be hereinafter described and claimed for carrying out the above-stated objects and such other objects, as will he apparent from the following description of preferred forms of the invention, illustrated with reference to the accompanying drawings wherein:

FIGURE l is a schematic view of a transmission with which my improved hydraulic controls may be used;

FIGURE 2 is a schematic illustration of the manner in which FIGS. 2A, 2B, 2C and 2D may be placed together to form a showing of the hydraulic transmission controls embodying the principles of my invention;

FIGURES 2A, 2B, 2C and 2D are schematic illustrations of parts of my improved hydraulic controls which should be placed together in the manner illustrated in FIG. 2;

FIGURE 3 is a schematic illustration of a modified part of my transmission controls; and

FIGURE 4 is a view taken on line 4-43 of FIGURE 3.

Like characters of reference designate like parts in the several views.

The transmission with which my improved hydraulic controls are adapted to cooperate m-ay be seen in FIG. 1 `to comprise a drive shaft 25, a driven shaft .26 and intermediate shafts 27 and 28. The shaft Z5 may be the usual crank sha-ft of the engine 29 of the vehicle, and the shaft 26 may be connected with the usual driving road wheels 30 of the vehicle by any suitable well-known power transmitting mechanism. The shafts 27 and 2S are in effect piloted with respect to the shafts 25 and 26. 'Ihe transmission comprises in general a hydraulic torque converter 3i, -hydraulically operated friction clutches 32 and 33., hydraulically operated friction brakes 34 and 35 and a planetary gear set 36.

The hydraulic torque converter 31 comprises a vaned impeller element 37, a vaned rotor or driven element 3S, and a vaned stator or reaction element 39. The impeller 37 is driven from the drive shaft 25, and the rotor 3S is fixed to the intermediate shaft 27. The stator 39 is rotatably disposed on a stationary sleeve 40, and a oneway brake 41 is disposed between the stator and the sleeve 40. The one-way brake 41 may be of any suitable construction, and, in the illustrated embodiment,

3 comprises a plurality of tiltable` sprags 42 disposed between an inner race surface 43 fixed with respect to the sleeve 40- and an outer race surface 44 xed with respect to the stator 39. The one-way brake 41 is so arranged as to -allow a free rotation of the stator 39 in the forward direction, that is, in the sa-me direction in which the drive shaft rotates and which is indicated by the arrow 45 and prevents a rotation of the stator in the reverse direction.

The torque converter 31 functions in a manner Well known for such torque converters for driving the rotor or driven element 38 at an increased torque with respect to the torque impressed on the impeller 37 of the converter. The vanes of the stator 39 function to change the directional flow of uid between the rotor and impeller so as to provide this increased torque on the driven element 3S. In this case, the reaction on the stator 39 is in the direction reverse to the direction of rotation of the drive shaft 25, so that the one-way brake 41 engages and prevents rotation of the stator in this direction. When the speed of the rotor 38 reaches a predetermined value, the reaction on the stator vanes 39 changes in direction, tending to rotate the stator in the forward direction; and the brake 41 releases and allows such rotation of the stator. In this case, the torque converter 31 functions as a simple fluid coupling which drives the rotor 38 at substantially the same speed and with no increase in torque with respect to the intpeller 37.

The planetary gear set 36 comprises a sun gear 46 which is fixed on the shaft 28, a second sun gear 47 fixed on a sleeve portion 43 which is rotatable on the shaft 28, a ring gear 49 fixed with respect to the driven shaft 26, a plurality of planet gears 52, a plurality of planet gears 51, and a planet gear carrier 52. Each planet gear 50 and each of the planet gears 51 is rotatably disposed and carried by the carrier 52. The carrier 52 is rotatably disposed with respect to the shaft 28 and the shaft portion 48 by any suitable bearings. The planet gears 51 are each in mesh with the sun gear 46 and also with a planet gear 50. The gears 50 are also in mesh with the ring gear 49 and with the sun gear 47.

The clutch 32 is arranged to connect the shaft 27 driven by the rotor 38 with the shaft 28 and the sun gear 46 fixed thereon. The clutch 32 comprises clutch discs 53 splined on a hub member 54 which is fixed on the shaft 28. The clutch also comprises clutch discs 55 interleaved between the discs 53 and fixed within a member 56 that isv in turn fixed to the shaft 27 so as to be driven by this shaft.

The clutch 32 comprises a movable pressure plate 57 splined within `the member 56 and adapted to press the friction discs 53 and 55 together in frictional engagement between it and an 'enlarged annular part 58 of the shaft 27. An annular piston `59 is provided for actuating the movable pressure plate 57. The pressure from the piston 59 is transmitted to the pressure plate 57 through a spring strut 60 which is in the form of an annular Belleville washer. The strut 60 at its inner periphery is acted on by the piston 59j so that its inner pheriphery .moves axially with respect to its outer periphery and moves -the pressure vplate 57 which is acted on by the strut 60 at lintermediate points thereof. The inherent resilient ac- -tion of the strut 6i) functions -to return the piston 59 back yinto its illustrated position when fluid pressure, applied as will be hereinafter described, is released from the piston.

The clutch-33 is arranged to connect the part 56 and thereby the shaft 27 with the shaft portion 48 and the sun -gear 47 and comprises clutch discs 61 splined onto the member 56 and clutch discs 62 splined within a member 63 which is xed to the shaft portion 48. A pressure plate portion 64 is fixed to the member 63 on one side of the clutch discs, and an annular hydraulic piston 65 is provided on the other side of the discs for compressing the discs between it and the pressure plate portion 64. A

return spring 66 is provided `for acting on the piston 65 and yieldingly holding it in its clutch disapplying position.

The brake 34 comprises a brake band 67 adapted to be contracted on the part 63 for thereby braking the sun gear 47. The brake 35' comprises a brake band 68 adapted to be contracted Von a drum portion 69l of the planet gear carrier 52.

In operation, the transmission has a neutral condition and provides low, Vintermediate and high speed ratios in forward drive and a drive'in reverse. The transmission is in neutral condition when the clutches 32 and 33 and the brakes 34 and 35 are disengaged.

The low speed forwardk drive may be obtained by engaging the clutch 32 and the brake 35. The c-lutch 32 is engaged by applying fluid pressure to the piston 59. The low speed power train exists from the drive shaft 25 through the torque converter 31, the intermediate shaft 27, the clutch 32, the shaft 28 and the planetary gear set 36 to the shaft 26. The brake 35 is eective on the carrier 52, so that the carrier -52 constitutes the reaction element of the gear set. The shaft 28, driven as just described, drives the sun gear 46 which thus constitutes the driving element of the gear set 36. The drive is transmitted through the planet gears 50 and 51 from the sun gear 46 to the ring gear 49 thus driving the shaft 26 at a reduced speed with respect to the shaft 28. Torque conversion takes place in both the hydraulic torque converter 31 and also in the gear set 36, so that the torque with which the shaft 26 is driven is the product of the torque multiplications of the hydraulic torque converter 31 and the gear set 36. It will be understood, as above described, however, that the torque conversion produced by the hydraulic torque converter 31 decreases as the speed of its driven element 38 increases,'and eventually the torque converter 31 functions as a simple uid coupling producing no torque conversion within it.

The intermediate speed power train is completed by allowing the clutch 32 -to remain engaged and engaging the brake 34 in lieu of the brake 35. The ow of power for the intermediate speed power train is the same as for the low speed power train; however, for the intermediate speed power train, the sun gear 47 is the reaction element of the gear set 36 rather than the carrier 52, the gear 47 for the intermediate speed drive being held stationary by the brake 34. Since there are sets of two planet gears 50 and 51 between the sun gear 46 and the ring gear 49; and since the sungear 47 is in mesh with the gears 50, the ring gear 49 and thereby the shaft 26 are driven at a reduced speed with respect to the shaft 28 which is, however, higher than for the low speed drive.

The high speed power train is obtained by allowing the clutch 32 to remain engaged and engaging the clutch 33 in lieu of the brake 34. The clutch 33 may be engaged by applying fluid pressure to its piston 65. In this drive, the shaft 27 is driven through the torque converter 31 from the drive shaft 25 as in intermediate speed drive. The shaft 27 is connected through the clutch 32 to drive the sun gear 46 as was the case in intermediate speed drive. The clutch 33 functions to connect the part 56, which is connected to the shaft 27, with the part 63 and thereby with the sun gear 47. Thus both the sun gear 46 and also the sun gear 47 are driven by the shaft 27, and as is well known in connection Ywith planetary gear sets, when two elements of the gear set are driven at the same speed, the gear set becomes locked up so that all of its gears and elements rotate as a unit. There is thus a direct drive between the shafts 27 and 26. The converter 31 may be expected to function as a simple fluid coupling, generally, in this drive; and there thus exists a susbtantially direct drive between the drive shaft 25 of the trans` mission and its driven shaft 26.

Reverse drive may be obtained through the transmission by engaging the brake 35 and the clutch 33. The power train for this drive is from the drive shaft 25 through the torque converter 31, the intermediate shaft 27,y the clutch,

49 to the driven shaft 26. The brake 35 causes the planet gear carrier 52 to function as the reaction element of the gear set; and, since there are only the single planet gears 50 between the sun gear 47 which drives and the ring gear which is driven, the ring gear 49 and the shaft 26 will be driven at a reduced speed in the reverse direction with respect to the shaft 27. For this drive, the torque converter 31 generally functions to increase torque; and thus the torque impressed on the shaft 26 is the product of the torque increases by the torque converter 31 and the planetary gear set 36.

It is believed that the construction of the transmission will be apparent from the diagrammatic illustration in FIG. 1 and that a person skilled in the art can supply the various detailed parts, such as bearings, to build an actual device; however, for an actual illustration of such detailed parts, the co-pending application of Robert W. Wayrnan, Serial No. 166,136, led June 5, 1950, which discloses a similar transmission, may be referred to.

The hydraulic control system for the transmission comprises in general la front pump I100, a rear pump 101, a manual valve 102, a downshift valve 103, a throttle valve 104, a compensator valve 105, a throttle modulator valve 106, a main oil pressure regulator valve 107, a low oil pressure regulator valve 108, a rear servo apply regulator valve 109, a 2-1 control valve 110, a front servo release control valve 111, la 2-3 shift valve 112, `a 3-2 control valve 113, a 1-2 shift valve 114, a range control valve 115, and a governor valve 116.

The brake 34 is applied by means of a hydraulic motor 117. The motor 117 comprises a piston 118 connected by means of a bell crank 119 and a strut 120 with one end of the brake band 67, the other end of the brake band 67 being held xed by means of a strut 121. The motor 117 has -a brake applying fluid pressure cavity 122 and a brake dis'applying fluid pressure cavity 123, and a spring 124 acts on the piston tending to hold it in its brake disapplying position. Fluid pressure supplied to the cavity 122 moves the piston 118 against the spring 124 so as to 'move one end of the brake band 67 to engage it with the drum 63. It may be noted at this point that the direction of reaction on the sun gear -47 and the drum 63 is in the reverse direction as indicated by the arrow A when the brake 34 is engaged for the intermediate speed ratio power train. This direction is opposite the direction of rotation of the drive shaft 25 indicated by the arrow 45, and the drum 63 in tending to rotate in this direction augments the action of the strut 120 in engaging the band 67 and causes increased band engagement, since the drum 63 tends to carry the end of the band acted on by lthe strut 120 in the same direction in which this end of the band is urged by the strut 120. Itis apparent that the band 67 wraps or is partially self-energizing for this lrotative tendency of the drum 63.

The brake 35 is engaged by means of a fluid pressure motor 125 which comprises a piston 126 movable by iluid pressure applied thereto against the action of a spring 127. Motion of the piston 126 is transmitted to one end of the brake band 68 by means of a bell crank 128 and a strut 129, theV other end of the brake band 68 being held fixed by means of a strut 130. In low speed drive through the transmission, the reaction on the planet gear carrier 52 and on the drum 69 is in the reverse direction as indicated by the arrow B, and this reaction or tendency to rotate tends to unwrap the band 68 with respect to the drum 69. For this direction of reaction, the brake 35 is thus self-deenergizing and provides a less braking effect than for a case in which this reaction did not exist. The reaction on the brake drum 69 for reverse drive is in the forward direction as indicated by the arrow C, that is, in the same direction as the drive shaft 25 rotates. The tendency of the drum 69 to rotate in this direction assists the strut 129 in forcing the movable end of the band 68 to move in the direction indicated by the arrow C, and

` 6 the brake 35 thus wraps or is self-energizing for this direction of reaction, so that the braking effect is greater than would be the case if there were no tendency for theV drum to rotate. The reaction on the drum 69 is greater for reverse drive than for low forward drive, and hence the brake 35 has been constructed to wrap for the reaction for reverse drive instead of that for low speed forward drive.

The pump may be of any suitable fixed displacement type and may comprise an outer gear 133 and an inner gear 134 and a crescent shaped casing portion 135 between the gears. The gears 133 and 134 carry iluid between their teeth and across the inner and outer surfaces of the casing portion 135 so as to draw uid from an inlet conduit 136 and discharge it into an outlet conduit 137. The inlet conduit 136 is adapted to draw fluid, such as oil, from a sump 138. The pump 100 is driven Vdirectly from the drive shaft'ZS through the impeller 37.

The pump 101 is of the same construction as the pump 100 and is driven from the driven shaft 26 of the transmission. The pump 101 draws iuid from the sump 138 through an inlet conduit 139 and discharges it into an outlet conduit 140.

A conduit 141 constitutes the supply or line pressure conduit for engaging the power train completing friction clutches and brakes and also for supplying various valves in the transmission control system with fluid pressure. A check valve 142 is disposed between the conduits 140 and 141 and comprises a piston 143 yieldably held in its closed position by means of a spring 144. The check valve 142 blocks fluid flow through the conduit 141 to the conduit and the rear pump 101.

A similar chk valve 145 comprising a piston 146 and a spring 147 acting on the piston is provided between the line pressure conduit 141 and the outlet conduit 137 for the front pump 100. The check valve 145 functions to prevent iluid ow from lthe line pressure conduit 141 to the conduit 137 when the pressure in the latter conduit is lower than in the conduit 141.

VThe main pressure regulator valve 107 functions to regulate pressure in the line pressure conduit 141. The valve 107 comprises a piston 148 having lands 149, 150, 151 and 152. A spring 153 is provided for `moving the piston 148 `downwardly as seen in the glre. The valve 107 comprises` ports 154, 155, 156, 157, 158 and 159. The ports 156 and 157 are connected with the line pressure conduit 141, and the port 154 is connected with the outlet conduit 137 of the pump 100. The ports 155 and 159 are permanently connected aroundl the piston 148.

The valve 108 is a regulator valve for regulating the pressure within the hydraulic torque converter 31. The valve 108 comprises a valve piston 160 having lands 161, 162 and 163. A spring 164 is provided between the land 161 and a stationary part for yieldably holding the piston downwardly. The valve 108 comprises ports 165, 166, 167, 168, 169 and 170. The port 165 is connected with the ports 159 and 155 which are in permanent connection around the valve piston 148 and also with the torque converter 31 through a torque converter inlet conduit 171; the port 166 is connected with the port 158 of the valve 107; the port 167 is a bleed port adapted to discharge into the sump 138; the port 168 is connected by means of a torque converter outlet conduit 172 with the torque converter 31; Vthe port 169 is connected with a conduit 173 which supplies lubricating oil to any suitable parts of the transmission; and the port is connected by means of a conduit 174 with the pump inlet conduit 136.

The governor valve 116 is for the purpose of providing a speed responsive fluid pressure for causing Various ratio changes through the transmission. The governor valve 1.*16 comprises a casing 175 which is xed on the driven shaft 26 and a piston 176 slidably disposed in a cavity within the casing 175. The piston 176 is provided with lands 177 and 178. The governor valve 116 comprises ports 179, 180, 181 and 182. The ports 181 and 182 are bleed ports discharging into the sump 138. VAgovernor weight 183 extends through and is slidably disposed within the governor piston 176. The weight 183 has a spring retainer washer 184 fixed on its inner end, and a spring 185 extends between the retainer washer 184 and an internal shoulder formed within the piston 176 for yieldably holding the weight 183 and the valve piston 176 together in the relative positions in which they are illustrated.

The throttle valve 104, the compensator valve 105 and the throttle modulator valve 106 provide pressures that vary with the position of the accelerator of the vehicle for varying the shift points of the transmission and also varying the pressures that are applied to the various clutches and brakes of the transmission. The throttle valve'104 is under the control yof the downshift valve 103. The downshift valve 103 comprises a valve piston 186 having lands 187 and 188. The downsbift valve 103 comprises ports 139, 190 and 191. The port 190 is connected with .the line pressure supply conduit 141. The valve piston 186 is under the control of the vehicle accelerator 192 by any suitable connecting mechanism, so that when the accelerator 192 is moved toward an open throttle position, it coordinately moves the piston 186 to the right as seen in the drawing. 1t will be understood that the accelerator 192 has the usual connections with the carburetor of the Vehicle engine 29.

The throttle valve 104 comprises a piston 193 having lands 194, 195 and 196. The valve 104 comprises ports 197, 198, 199 and 200. A spring 201 is provided between the valves 103 and 104. The port 197 is connected with the line pressure supply conduit 141; the port 198 which is relatively restricted, is connected with the port 199; and the port 200 is a bleed port. A bleed port 202 is provided between the two valves 103 and 104.

The throttle modulator valve 106 comprises a piston 203 having lands 204 and 205. A sheet metal spring retainer 206 embraces an end of the piston 203, and a spring 207 is provided between the land 204 and the retainer 206. A spring 208 is provided between the land 205 and the ad jacent end ofthe cavity in which the piston 203 is disposed. The valve 106 lcomprises ports 209, 210', 211, 212, 213 and 214. The ports 209 and 211 are bleed ports, and the port 210 is connected with a throttle pressure supply conduit 215 to which the ports 198 and 199 of the throttle valve 104 are also connected.

The compensator valve 105 comprises pistons 216, 217 and 218. The piston 216 constitutes a Vsimple plug slidably disposed in a stationary sleeve 219'. The piston 217 com-prises lands 220, 221, 222 and 223. The piston 218 comprises lands 224, and 225. A spring 226 is Vdisposed between the land 220 and the xed sleeve 219, and a spring 227 is disposed between the land 220 and the movable plug 216. l

The compensator valve 105 is provided with ports 228, 229, 230, 231, 232, 233, 234, 235, 236 and 237. The port 229, which is relatively restricted, and the port 228 are connected by means of a compensator pressure supply conduit 238 with the ports 158 and 166 of the pressure regulator valves 107 and 108; the port 230 is connected by means of a conduit 239 with the port 213 of the valve 106; the port 231 is connected by means of a conduit 240 with the port 212 of the valve 106; the port 232 is connected with a governor pressure supply conduit 241 that is also connected with the port 180 of the governor valve 116; the ports 233 and 234 are connected with the line pressure supply conduit 141; the ports 235 and 236 are bleed ports; and the port 237 is also connected with the governor pressure supply conduit 241.

The various ranges of operation of the transmission are under th control of the manual valve 102. The valve 102 comprises a valve piston 242 having lands 243, 244, 245 and 246. The valve is provided with ports 247, 248, 249, 250, V251, 252, 253, 254 and 255. The port 248 is connected by meansof a" conduit 256 and a branch con- Y duit 257 with the'piston59 for the front clutch 32 and with the port 179 of the governor valve 116, respectively; the port 249 is connected by means of a conduit 258 with thefront brake apply cavity 1220i the brake servo motor 117; the ports 250 and 251 are connected with the line pressure supply conduit 141 by means of a branch conduit 259; the port 252 is connected by means of a conduit 260 with thev port 191 of the downshift valve 103; the port 253 is connected bymeans of a'conduit 261 with the port 214 of the throttle modulator valve 106;` andthe port 254 is a bleed port. The manual valve piston 242 is controlled from the drivers compartment by means of a selector lever 262 Vlocated directly beneath the vehicle steering wheel 263, the selector lever being connected by any suitable connecting mechanism with the piston 242 so that the piston 242 can be moved into any of its principal positions which are R, N, D2, D1" and L corresponding toV reverse, neutral, high range drive with the Vstart in intermediate, high range drive with the start in low, and low range, respectively.

The 2-3 shift valve 112 causes engagement and disengagement of the proper clutch and brake (clutch 33 and brake 34) for causing changes between second and third speed drives. The valve 112 comprises pistons 264, 265 and 266. The piston 264 is a simple plug. The piston 265is provided with lands 267, 268 and 269. A spring 270 is disposed between the land 267 and a stationary part for urging the piston 265 Vupwardly and a spring 271 is provided between the land 267 and the piston 264. The piston 266 is provided with lands 272 and 273. The valve 112 is provided with ports 274, 275, 276, 277, 278, 279, 280, 281, 232, 233 and 284. There are two ports 274 which are connected together and with the throttle pressure supply conduit 215; the ports 275 and 277 are connected together; there are two ports 276 connected together and by means of a conduit 285 with the port 139 of the downshift valve 103; the ports 278 and 281 are connected with the governor pressure supply conduit 241 by means of a branch conduit 286; vthe port 279 is connected with the piston 65 for the rear clutch 33 by means of a conduit 287; the port 280. is a bleed port; the port 282 is connected by means of a .branch `conduit 288 with the conduit 257 and thereby with the port 248- Vof the manual valve 102; the port 283 is connected with the conduit 261 and thereby with the port 253 of themanual valve `102; and the port 234 is connected by means of a conduit 289 with the port 247 of the manual valve 102.

The 1 2 shift valve 114 causes engagement and disengagement of the brakes 34 and 35 for Vcausing changes between irst and second speed drives. The valve 114 comprises a valve piston 290 provided with lands 291, 292, 293,294 and 295. The 1 2 shift valve comprises ports 296,297, 298, 299,Y 300, 301, 302, 303, 304, 305 and 306. The ports 296 and 297 are connected together; the port 299 is connected by means of a conduit l307 with the port 252 of the manual valve 102; the ports 300, 303 and 306 are bleed ports; the port 301 is connected by means of a conduit '308 and the conduit 258 with the port 249 of the manual valve 102; the port 304 is connected by Ymeans of a conduit 309 with one of the ports 276 of the 2-3 shift valve 112; and the port 305 is connected by means of a conduit 310 with the ports 275 and 277 of the 2-3 shift valve 112. A spring 311 is provided, acting on the lower end of the piston 290 urging it upwardly.

The range control valve 115 is under the control of the manual valve 102 and determines the starting speed drive for high range operation. The range control valve port 255 of the manual valve 102; the port 315 is connected with the governor pressure supply conduit 241; and the ports 316 and 317' are connected together and are con- 9 nected by means of a conduit 319 with the port 298 of the l-2 shift valve 114.

The RSA or rear servo apply regulator valve 1109 is provided for the purpose of reducing by regulation the pressure applied to the servo motor 125 for the rear brake 35 in accordance with varia-tions of throttle pressure and accelerator position. The valve 109 comprises valve pistons 320 and 321. The piston 320 is a simple plug, and the piston 321 comprises lands 322 and 323. A spring 324 is provided between the upper end of the piston 321 and the adjacent end of the cavity in which the piston is disposed. The valve 109 comprises ports 325, Vv326, 327, 328 and 329. The port 325 is connected by means of a conduit 330 having a restriction 331 therein with the port 302 of the 1-2 shift valve 114; the port 326 is connected with the throttle pressure supply conduit 215; and the ports 328 and 329 are connected with the servo motor l125 for the rear brake 35 by means of a conduit 332.

The 2-1 control valve 110 is provided for controlling the application of iluid to the servo motor 125 for the rear brake 35. The 2-1 control valve comprises a piston 333 having lands 334, 335 and 336. A spring 337 is .pro-vided at the lower end of the piston 333 and yieldably holds the piston 333 to the limit of its movement upwardly as seen in the drawing. The Valve 110 comprises ports 338, E339, 340, 341, 342 and 343. f'I'he ports 338 and 340 are connected together and are connected by means of a branch conduit 344 with the lower end of the restriction 331; the port 339 is connected by means of a branch conduit 345 with the upper end of the restriction 331; and the port 341 is a bleed port.

The 3-2 control valve 113 functions to restrict fluid ow at times to the disapply cavity V123 of the servo motor 117 for the front brake 34 for assuring a smooth, light throttle, shift from third speed ratio to second speed ratio. The 342 control valve comprises a piston 346 having lands 347 and 348. A spring 349 acts on the piston 346 yieldably holding it at the limit of its movement upwardly as seen in the drawing. The valve 113 comprises ports 350, 351, 352 and 353. The port 350 is connected by means of a branch conduit 354 with the throttle pressure supply conduit 215, the ports 274 and the port 343 of the valve l110; the port 351 is connected through a restriction 355 with the conduit 287; the port 352 is connected with the conduit 287; and the port 353 is a bleed port.

The FSR or front servo release control valve 111 functions to either connect the 2-1 control valve 110 or else the 3-2 control valve 113 with the disapply cavity 1123 of the servo motor 117 for the front brake 34. The FSR control valve 111 comprises a valve piston 356 having two ends 357 and 358 of reduced diameter. The valve comprises ports 359, 360, 361 and 362. The port 359 is connected by means of a conduit 363 with the port 342 of the 2-1 control valve'110; the ports 360 and 36.1 are connected together and are connected by means of a conduit 364 with the disapply cavity 123 of the front Ibrake servo motor 117; and the port 362 is connected by means of a conduit 365 with the port 351 of the 3-2 control valve 113.

The downshift valve piston 1'86, instead of being controlled directly from the accelerator '192, may be controlled from and by means of the vacuum existing in the carburetor and in the manifold of the vehicle engine 29. Such mechanism under the control of these vacuum pressures causes the downshift valve piston 186 to be moved proportionally to the movement given the accelerator pedal 192 so that substantially the same pressures are realized from the throttle valve 104 with this manner of control as in the case in which the accelerator is directly effective on the downshift valve piston 186 as illustrated and previously described.

The vacuum controlled mechanism for the Adownshift valve piston 186 and for the throttle valve 104 is illustrated in FIGS. 3 and 4 and comprises a vacuum motor 400. The vacuum motor 400 comprises a casing* portion 401 and a second casing portion 402 iixed thereto. A diaphragm 403 of flexible material is clamped between the casing portions 401 and 402. The casing portion 401 is provided with a vent 404 to atmosphere on o-ne side of the diaphragm 403, and the casing portion 402 is provided with a port 405 adapted to be connected to a source of vacuum.

The diaphragm 403 is fixed to an armature 406 at the center of the diaphragm. The diaphragm is mounted between a sheet metal disc 407 on one side of the diaphragm and a hollow sheet metal cup 408 on the other Side of the diaphragm, and a screw 409 extends into the armature 406 and through the cup 408, disc 407 and diaphragm 403 for clamping the diaphragm between the disc 407 and cup 408 and fixing it with respect to the armature 406.

An elelctrtic winding 410 is disposed in the casing portion 401, and the armature 406 is adapted to move into the winding 410. The winding 410 is grounded at one end 411, and at its other end it is connected to an electric lead 412.

A sleeve 413 having a tapered end surface 414 extends through the casing portion 401 and partially into the winding 410. The armature 406 has a tapered end 415 adapted to come into contact with the tapered surface 414 on the sleeve 413 when the armature 406 moves into the winding 410. The armature 406 acts on a thrust rod 416 extending through the sleeve 413, and a spring 417 is disposed within the cup 408 and within the casing portion 402 to urge the armature 406 into abutting contact with the thrust rod 416. .A dust proofing -iboot 418 of rubber-like material is disposed about the sleeve 413 and thrust rod 416.

The thrust rod 416 is coupled with the downshift valve piston 186 by means of a lever 419 and a thrust rod 420. The lever 419 is pivoted on a stationary stud 421, and the thrust rod 416 extends into a slot 422 provided in one end of the lever 419. The thrust rod 420 extends through an opening 423 provided in the other end of the lever 419 and extends into a slot 424 provided in the outer end of the downshift valve piston 186.

The lead `411.2 is connected to a kickdown switch 425 which is also connected with the usual ignition switch 426 of the vehicle. The ignition switch 426 has the conventional connection with the vehicle battery 427 which has one of its terminals grounded. The kickdown switch 425 has two contacts 428 and 429 adapted to be bridged and connected by means of a switch blade 430. The blade is acted on by a spring 431 and is held thereby out of bridging relationship with respect to the contacts 428 and 429 and is provided with a stud 432 adapted to be acted on by the vehicle accelerator 192. The accelerator 192 has a conventional pivotal connection 433 with a stationary part of the vehicle for allowing depression of the accelerator by the foot of the operator in accordance with usual custom.

The carburetor of the vehicle engine 29 has the usual throttle plate or butterfly valve 434. The throttle plate 434 is ixed on a pivotally mounted shaft 435 in the relatively large diameter carburetor pass-age 436 located between the relatively restricted carburetor throat 437 and the usual fuel intake manifold 438 connectedto the cylinders of the internal combustion vehicle engine 29. A throttle lever 439 is fixed on the shaft 435 outside of the carburetor for opening the throttle plate 434. A stop pin 440 is provided cooperating with the lever 439 for limiting the throttle opening movement of the throttle plate 434 to a wide open throttle position as shown in dotted lines, through an angle of movement of substantially inthe particular embodiment illustrated.

A link 441 is connected between the throttle lever 439 anda lever 442 which is liXed with respect to the accelerator pedal 192 to swing therewith about the pivotal mounting 433 of the pedal 192. A lost motion connection 443 of any suitable type is provided in the link 441. The lost motion connection 443, as illustrated, comprises a shell 444, a disc 445 slidably disposed in the shell 444, and -a compression spring 446 disposed between Vthedisc 445 and the closed end of the shell 444. The arrangement is such that the throttle plate 434 is moved from its illustrated throttle closing, engine idling position, to its fully open throttle position in which the throttle lever 439 contacts the stop pin 440 by a depression of the accelerator 192 due to force transmitted through the lever 442, the lost motion connection 443 and the link 441 to the throttle lever 439. Such movement of the throttle plate 434 is without yielding of the spring 446 in the lost motion connection 443 and before contact of the accelerator 192 with the switch stud 432. When the accelerator is moved still farther out of and beyond its fully opened throttle position, such movement is by virtue of a yielding by the spring 446 and the lost motion connection 443sV without any additional movement of the throttle lever 439 and throttle plate 434, and the accelerator 19-2 in such movement contacts the switch stud 432 and moves the switch blade 430 into contact with the switch contacts 428 and 429.

The port 495 of the motor 488 is connected by means of a vacuum conduit 447 with both the manifold 438 and also with the carburetor passage 436. The conduit 447 is connected with a branch passage 448 which is connected with the manifold 438 through a restricted opening 449. The`conduit 447 isalso connected with a branch passage 458 which is connected with the carburetor passage 436 by means of a restricted opening 451. It will be noted that the restricted opening 451 is disposed immediately beneath one edge of the throttle plate 434 when the plate is in its throttle closing, engine idling, posltion 1n lwhich it is shown in full lines. The connection of the Vacuum motor 400 with both the manifold 438 and also with the throttle opening 436 provides a vacuum pressure in the conduit 447 that varies much more closely with torque demand by the vehicle operator as evidenced by the depression of the vehicle accelerator 192 than the pressure that exists in the manifold 438 alone. The restricted opening 451 is preferably smaller than the restricted opening 449, and in an actual embodiment, satisfactory operation was obtained with the restricted opening 451 being .028 inch vin diameter and the restricted opening 449 being .O32 inch in diameter.

In operation, referring to FIGS. Al, 2 and 2A to 2D, the transmission is maintained in its various ranges under the control of the manual valve 102. The transmission 1s m neutral conditon when the manual selector valve piston V242 in its N or neutral position. When the engine 29 -begins operating, the pump 100l driven b-y the engine supplies line pressure to the conduits 137 and 141 and-con nected conduits, pumpingoil from the sump 138 through the pump inlet 136. The conduit 141 is connected with the-'conduit 137 through the check valve 145, the check valve 145 being held open by the iiuid pressure from the pump 108. This iiuid pressure in the conduit 141 holds the vcheck valve 142 closed so that fluid cannot .escape through the rear pump 101, which is assumed inoperative at this time with the vehicle being stationary. In the neu- Ytral position of the piston 242, the groove between the lands 244 and 245 connects the ports 250`and 251 supplied with line pressure through the conduits 259 and 141, and the lands block flowof line pressure 'to any of the other ports in the manual valve 102. The manual valve piston 242 thus prevents application of tiuid pressure to the engaging pistons for any of the power train completing clutches and brakes of the transmission'.

The main oil pressure regulator valve 107 functions for all conditions of the transmission and its hydraulic control system to regulate the line pressure in the conduit 141 and connected conduits to predetermined m-aximumvalues. For this purpose, the line pressure from the conduit `141 is supplied through the.port 157 between the lands 151 and 152; and, since the land 151 isof larger diameter than the land 152, the line pressure applied to these lands tends to move the regulator valve piston 148 upwardly against the action of the spring 153. This movement of the piston 148 tends to release the line pressure from the conduit 141 between the lower edge of the land 150 and edges of the ports and 159 into the converter supply conduit 171. Thespring 153 is of such strength that the ports 155 and 159 will not be thus opened by line pressure influence on the valve vpiston 148 until a certain fixed value of line pressure is reached. This value of line pressure is maintained b-y theV valve 187 in thus metering and relieving excess fluid under pressure from the conduit 141, assuming that there are no other iniluences on the piston 148 than just mentioned.

For most conditions of operation, however, an additional variable force is applied to the piston 148 tending to move it, and this third force is due to fluid pressure of diiferent values (which may be termed compensator pressure) applied to the lower end of the piston 148 through the port 158 and conduit 238. For the neutral condition of the transmission when the accelerator 192 is in its closed throttle, relaxed position; the compensator pressure is equal to full line pressure which is supplied to the lower end'of the piston 148 through the port 158. Line pressure ows from the conduit 141 through the port 234 of the compensator Valve 105, the groove between the lands 220 and 221, the port 228 and the conduit 238`to the port 158.Y Line pressure is supplied from the compensator pressure conduit 238 through the port 229 on tothe lands 221 and 222; and, since the land 221 is larger than the land222, this line pressure tends to move the compensator valve piston 217 to the left against the action of the springs 227 and 226. However, for this condition ofoperation, the springs acting on the piston 217 are of suliicient strength to hold the piston to the limit of its movement to the right.

The fluid pressure applied to the main oil regulator valve piston 148 on its lower end provides a force acting against the spring 153 tending to move the piston 148 upwardly as seen in the ligure to more fully open the ports 155 and 159 to the groove between the lands 150 and 151. The full line pressure applied to the lower end of the piston 148 thus maintains the line pressure in the conduit 141 and connected conduits at a predetermined minimum, which for one certain embodiment of the invention is 75 pounds per square inch.

The secondary main regulator valve 108 regulates the fluid pressure Within the conduit 171 and thereby within the torque converter 31 to which the conduit 171 supplies fluid pressure. The pressure in the ports 155 and 159 and in the conduit 171 and between the lands 150 and 151 of the main regulator valve piston 148 is applied between the lands 161f and 162 of the low oil pressure regulator valve piston through the port 165. Since the'land 161 is larger than the land 162, this iluid pressure tends to move the piston 160 upwardlylagainst the action of the spring 164 toopen up the port 169 and meter iluidV between theV land 161 and an edge of the port 169. Thus, as the fluid pressure in the conduit 171 and in the converter 31 tends to increase, the excessive fluid pressure is discharged through the port 169; and the pressure in the conduit 171 and converter 31 is regulated to a predetermined maximum. Y

The conduit 173 is connected to various working parts of the transmission for lubricating them; and, when this conduit is lilled, the valve piston 160 moves slightly farther against the action of the spring 164 on a slight increase in pressure in the converter 31 so as to relieve fluid from Vthe port 168 through the groove'between the 'lands 162 and 163 and through the bleed port 167. At

this time, the regulating effect of the valve 108 takes place between the land 162 and the lower edge of the port 168, and the fluid ilows through the conduit 171 13 and through the torque converter 3'1 to the conduit 172 which is the fluid discharge conduit for the torque converter 31.

The compensator pressure in the conduit 238 is also applied to the valve piston 160 for changing the regulated Converter pressure in the conduits 171 and 172 and in the torque converter 31 for various conditions of operation of the transmission and controls. The pressure on the lower end of the valve piston 160 tends to move the piston 160 upwardly against the action of the spring 164 vto open the discharge port 168 for the torque converter to the bleed port 167 and to thus further relieve and decrease the pressure in the conduits 171 and 172 and converter 31. With full line pressure in the conduit 238 for conditions of operation just mentioned, the regulated converter pressure in the torque converter 31 is at a minimum, which, for one particular embodiment of the invention is substantially 30 pounds per square inch.

Under certain relatively abnormal conditions, as, for example, when the oil in the sump 138 is cold; the conduit 174 relieves the fluid pressure in the converter 31 and in its supply conduit 1'71. The resultant increasedV pressure due to cold oil in the conduit 171 applied to the relatively large land 161 will move the piston 160 still farther upwardly against the action of the spring 164 so as to connect the ports 170 and 165 by means of the groove between the lands 161 and 162. In this case, the regulating action by the valve piston 160 is by virtue of a metering effect between the lower edge of the land 161 and the port 170, and the excessive iluid owing through the port 170 Hows directly through the conduit 174 to the inlet 136 of the pump 100.

The transmission and its control system are conditioned for operation in D2 range, that is, in automatic range in which the vehicle is started in intermediate speed drive, r

by moving the manual selector valve piston 242 into its D2 position. In this position, the piston 242 provides a connection between the ports 255, 247, 248i, 249 and 250 by means of the groove between the lands 243 and '244. The port 250 carries line pressure, being connected with the line pressure supply conduit 141 by means of the branch conduit 259. Line pressure is thus supplied to the ports 255, 247, 248 and 249.

The line pressure from the port 255 flows through the connected conduit 318 to the port 314 of the range control valve 115. Line pressure lis thus supplied on the lower end of the piston 312 of the range control valve and moves this valve piston to the limit of its movement upwardly thereby connecting the port 317 with the port 314. Line pressure is thus `supplied to the port 317 and to the port 298 of the 1-2 shift valve 1114 through the conduit 319. Line pressure is supplied from the lport 298 to the upper end of the 1-2 shift valve piston 290 and moves the piston downwardly against the action of the spring .311 to the limit of its movement in this direction. As will be apparent from subsequent description of operation, the l-2 shift valve has a low speed position and a second speed position which are respectively to the limit of its movement upwardly and to the limit of its movement downwardly, and this application of line pressure to the upper end of the l-Z shift valve piston 291)1 holds this piston in its second speed position so that first speed cannot be operative in the D2 range.

The line pressure supplied through the port 247 of the manual valve 102 provides line pressure to the port 284 of the 2-3 shift valve 112through the conduit 289. This line pressure supplied to the 2-3 shift valve 1.12 is subsequently used, on a shifting of the 2-3 shift valve piston 265 out of the second speed position of this piston, in which it is illustrated, downwardly to its high speed position, `for engaging the rear clutch 33 for direct drive as will be subsequently explained.

The line pressure supplied to the port 248y of the manual valve 102 ilows through the conduit 256 to the piston 59 of the yfront clutch 32 `and thus applies this clutch. Line pressure from the port 248 also ows through the branch conduit 257 to the governor valve 116, particularly to the fluid inlet port 179 of the governor valve 116. The valve 116 modulates and regulates the line pressure supplied to the port 179, producing a governor pressure in the port 18@ and in the governor outlet conduit 241 that increases with vehicle speed, as will be subsequently explained. Line pressure from the port 248 of the manual valve 102 also flows through the branch conduit 288 to the port 282 of the 2-3 shift valve -112 for purposes to be subsequently explained.

r'he line pressure supplied to the port 249 of the manual valve 152 flows through the conduit 25S to the brake apply cavity 122 of the front brake servo motor 117. The line pressure acting on the piston moves the piston against the action of the spring 124 and applies the brake band 67 on its drum by means of the lever 119 and the strut 125. Thus the brake 34, as well as the front clutch 32, are engaged; and the intermediate speed power train through the transmission is completed. Line pressure also tlows from the port 249 of the manual valve 102 through the conduit 358 to the port 351 of the l-2 shift valve `114; however, in the intermediate speed position of the piston 294) in which the piston is `disposed at this time, the land 294 blocks the port 30,1; and the tluid pressure applied to this port thus has no effect.

When the intermediate speed power train is completed -as just described by engagement of the clutch 32 and brake 34, the accelerator 192 is -assumed to be in its closed throttle position with the vehicle engine crank-shaft rotating at idling speeds. Under these conditions, insuiicient power is transmitted through the intermediate speed power train and in particular through the hydraulic torque converter 3-1 for driving the driven shaft 26 and the vehicle, and the drive may be rn-ade effective for driving the vehicle by simply depressing the accelerator 192 to open the engine throttle.

Throttle opening movement of the accelerator 192 also has other effects on the hydraulic control system, including an increasing or" the line pressure in conduit 141 and connected conduits for increasing the applying pressure for the brake 34 and the clutch 32, and throttle opening movement also eliects an increasing of the liuid pressure 'within the hydraulic torque converter 31.

The accelerator 192 acts on the throttle valve piston 193 through the intermediary of the downshift valve piston 186 to provide a throttle pressure in the conduit 215 which is less than the line pressure in the conduit 141 and which increases from zero at closed throttle position of the accelerator to line pressure at open throttle position. The throttle valve '104, like the valves 107 and `108, is a regulator valve providing a variable fluid pressure by metering liuid flow between a valve land and a valve port in accordance with variable forces impressed on the valve. The accelerator 192 tends to move the throttle valve piston 193 to the right yas seen in the iig-ure, upon depression of the accelerator, by means of the downshift valve piston `186 -and the spring 201. Such movement of the throttle valve piston 193 provides a connection between the ports 197 and 199 through the groove between the lands 194 and 195, admitting fluid under pressure into the conduit 215 through the port 199. The pressure in the conduit 215 iioWs back through the port 193 and is thus effective on the lands 195 and 196. Since the-land 195 is of larger diameter than the land 196, the ilu-id pressure on the lands tends to move the valve piston 193 back to the left against the action of the spring 201, `so that the land 195 tends to again close the port 197 and block further admittance of duid pressure to the conduit 215. The greater the depression of t-he accelerator, the greater will be the -force -from the spring 201 on the throttle valve piston 193', and the greater must be the pressure in the conduit 215 for closing the port 197 by the land 195, and hence the valve 104 h-as a regulating action to provide a throttle pressure in the conduit 215 which increases with accelerator depress1on.

The throttle pressure from the throttle valve 104 is supplied through the conduit 215 to the throttle modulator valve 1116 through the port 216. The valve 106 functions to provide a limited or so-called modulator pressure in the conduit 239. This limited pressure in conduit 239 is the same as the throttle pressure in conduit 215 up to a predetermined maximum value, and for further increases in throttle pressure corresponding to increased openings of the engine throttle, the modulator pressure in conduit 239 remains at this predetermined maximum value. The throttle pressure in conduit 215 flows through the port 210 of the throttle modulator valve and through the groove between the lands 2114 and 205- to the port 213 and the conduit 239. The spring 208 is a relatively light spring as compared to the spring 207, and this spring 208 functions to normally maintain the valve piston 203 in its illustrated position with the spring retainer 266 contacting the adjacent end of the bore for the piston 202 and with the spring 2117 holding the retainer 266 and the piston 263 at thelimit of their movement apart. The spring 20S under these conditions is substantially at its free length and assures that the ports 210 and 213 remain in communication by means of the groove between the lands 2114 and 2115 until the modulator pressure in the conduit 23.9 reaches its predetermined value.

The modulator pressure in the conduit 239 is applied to the lands 204 and 205, and since the land 204 is larger than the land 205, this fluid pressure tends t move the piston 203 to the left against the action of the spring 207, the spring retainer being bottomed under these conditions on the adjacent end of the cavity in which the piston 203 is disposed. When the fluid pressure in the conduit 239 reaches its predetermined maximum value, the pressure moves the piston 203 to the left and closes the port 21@ by means of the land 205, so that the pressure of the iiuid in the conduit 239 increases no further. In the particular embodiment of the invention mentioned before, the modulator pressure in the conduit 239 had a maximum of 22 pounds per square inch at about 25% throttle opening, and the modulator pressure remained constant for additional throttle opening movements of the accelerator.

The modulator pressure in the conduit 239 is applied to the compensator valve 105, which is a regulator valve, for providing a compensator pressure in the conduit 23S that decreases with depression of the accelerator pedal for initial throttle opening movements of the accelerator. The compensator pressure in conduit 238 also increases with the speed of the driven shaft 26 and the vehicle. In this connection, the action of the governor valve 116 in producing a governor pressure in conduit 241, which is connected to the compensator valve, will now be described.

The governor valve 116, like the valves 104, 105, 107 and 1118, is a regulator valve; that is, it produces an output pressure that varies gradually with changing forces on the valve. The casing 175 for the valve 116 rotates with the driven shaft 26 `of the transmission, and the valve piston 176 and weight 183 tend to move outwardly under the inuence of centrifugal force. The weight 183. in particular has a relatively large centrifugal force acting on it, and this force is transmitted to the hollow valve piston 176 by means of the spring 185 disposed between the piston 176 and the spring retainer 184. Line pressure is present in the conduit 257; and on outward movement of the valve piston 176, duid ows through the port 179, the groove between the lands l177 and 178, and the port 186 into the conduit 241 to supply pressure to the latter conduit. The pressure in the conduit 241 is applied to the facing ends of the lands 177 and 178; and, since the land 17S is larger in diameter than the land 177, this 217 to the left.

16 tiuidpressurertends to move the piston 176inwardly of lthe valve casing :175,.so that the land 177 will move over Vthe port 179 and block any further admission of duid pressure to the conduit 241. A balance is attained between the centrifugal force eective on the valve piston 176 tending to move the piston outwardly of the casing 175, which increases with vehicle speed, and the force drived from the fluid pressure in the conduit 241 elective on thelands 177 and 178 tending to move the piston Y176 inwardly, which increases withrthe pressure in the conduitr241, for every speed of the driven shaft 26. The valve piston 176 thus meters theow of duid under pressure to the governor. output conduit 241 between the land 177 and the inner edge of the port 179 and provide a regulated governor pressure in .the conduit 241 that increases with the speed of the driven shaft 26 and of the vehicle. The function of the spring `185 effectively between the weight 183 and the valve piston 176 is to allow the weight 183 to move outwardly of the casing 175 and radially with respect to the shaft 26 without correspond- ,ing movement of the piston 176 at the higher speeds of the shaft 26. This arrangement provides a governor Ypressure that increases more gradually with increases in pensator valve 165, when the vehicle is being started,

since line pressure is applied between the lands 224 and 225 from the conduit 141 and port 233. The governor pressure starts from zero when the vehicle is at a standstill and increases, while the line pressure is at some much higher value, such as pounds per square inch under the same conditions. Since the land 225 is larger than the land 224, .the piston 218 is held to the limit of its movement to the right out of contact with the regulating piston 227 until the governor pressure increases suiciently to overcome the effect of line pressure on the lands 224 and 225. The governor pressure in the conduit 241 is initially, at low speeds of the vehicle, effective through the valve piston 216 on the regulating piston 217. The governor pressure is applied through the port 237 on the piston 216, and force on the piston 216 is transmitted through the spring 227 to the piston 217 tending to move the latter to the right, the force so impressed on the piston 217 increasing with governor pressure and vehicle speed.

The modulator pressure in the conduit 239 that increases with accelerator opening to a predetermined maximum is impresesd on the lands 222 -and 223; and since the land 222 is larger than the land 223, this modulator fluid pressure tends to move the compensator piston This is just opposite to the effect of the increasing governor pressure in the conduit 241.

Line pressure is supplied tothe port 234 from the conduit 141, and the piston 217 functions to regulate so as to provide compensator pressure in the conduit 238. This compensator pressure increases with increasing governor pressure in the conduit 241 and decreases with increasing throttle pressure in the conduit 215 and modulator pressure in the conduit 239. The springs 226 and 227 tend to hold the piston 217-to the limit of its Vmovement to the right, Opening thev port 234Vby means of the groove between the lands 220 and 221 to the port 228 and the compensator conduit 238. Fluid thus flows into the compensator conduit 238. The compensator pressure in the conduit 238 ows through the port 229 between the lands 221 and 222 and tendsrto move the piston 217 to the left so as to close the port 234 by means of the land 221,

this return movement @i the piston 217 being by virtue of edge of the port 234, providing a certain regulated com-y pensator pressure in the conduit 238. The governor pres-I sure tends to move the piston 217 to the right as above described, so as to move the land 221 oi the port 234 and admit further fluid pressure to the compensator conduit 238. Thus, the compensator pressure in the conduit 238 increases with governor pressure and vehicle speed. The modulator pressure, as above described, tends to move the piston 217 to the left to close the line pressure supply port 234 by means of the land 221, and thus the compensator pressure in the conduit 238 decreases with increasing throttle pressure and modulator pressure.

The piston 218, at higher speeds of the vehicle, reduces the eiect of the governor-pressure just described in increasing the compensator pressure in the conduit 238. As the governor pressure in the conduit 241 rises, eventually it is suliicient so as to move the piston 218 to the left so that this piston acts on the piston 217 and tends to move the latter piston to the left against the action ofV the governor pressure transmitted through the piston 216. The piston 21S is moved to the left by the governor pressure when the governor pressure overcomes the eiect of the line pressure impressed through the port 233 on the lands 224 and 225 tending to move the piston 218 to the right. The line pressure in the conduit 141 and applied to the lands 224 and 225 decreases with increasing governor speeds, as will be hereinafter described, and there thus exists a crossing of the etiect of line pressure which decreases with increasing vehicle speed and governor pressure which increases with vehicle speed, both effective on the piston 218, after which the piston 218 is effective on the valve piston 217 and its regulating action.

When the vehicle begins to move, after the accelerator 192 has been moved toward its open throttle position to increase the speed and power output of the vehicle engine, the rear pump 101 beginsits pumping action and draws fluid through the intake conduit 139 from the sumpl 138 and discharges it into the outlet conduit 140. The check valve 142 remains closed until the pressure of the tluid discharged by the rear pump 101 increases to a sufcient value to overcome the forces due to the line pressure and the spring 144 on the piston 143; and at this time, the check valve 142 opens and the rear pump discharges into the line pressure conduit 141. The fluid flow through the line pressure conduit 141 then reverses and closes the check valve 145 by moving the piston 146 upwardly tonto its seat. The closing of the check valve 145 blocks discharge by the front'pump 100 into the line pressure conduit 141 and its connected conduits, and the rear pump now becomes the sole supply of line pressure for the conduit 141 and connected conduits. The line pressure in the conduit 141 is impressed on the main oil pressure regulator valve piston 148 and particularly its lands 151 and 152 through the port 157 to provide the regulating action between the land 149 and the port 154 when the front pump alone is providing the line pressure, and when the line pressure increases slightly due to closing ofthe check valve 145 and opening of the check valve 142 as just described, the piston 148 is moved upwardly of the ports 155 and 159, with the excess pressure pro-V duced by the rear pump 101 escaping trom the port 156 and the groove between the lands 150 and 151 to the ports 155 and 159. With the rear pump 101 being thus active to produce the line pressure, the line pressure is now regulated exactly as has been previously described, except that it is slightly higher in value and is metered between the land 150 and ports 155 and 159 instead of between 18 Y an edge of the port 154 and the land 149. The front pump now functions solely to supply iiuid under pressurel to the converter 31 and for lubrication. I

The compensator pressure in conduit V238, as it changes 6 with accelerator opening yand vehicle speed, causes a change in the line pressure regulating action of the main oil pressure regulator valve 107 as compared with its operation when the accelerator is in its closed throttle position and the vehicle is stationary. The pressure in 10 the conduit 238 is impressed on the lower end of the main oil pressure regulator valve piston 148 through the port 158 and tends to move the piston 148 upwardly against its spring 153 to more fully .open the port 154 or the ports 155 and 159 depending on which of thesey ports is-regulating, with the driven shaft pump 101 being inactive in one case and activein the other case. The piston 148 thus vents the line pressure conduit 141'less and maintains the line pressure in the conduit 141 at a higher value as the compensator pressure inA the conduit 238 decreases and acts conversely to maintain line pressure at a lower value as the compensator pressure increases.

As has beenexplained, the compensator pressure v1n the conduit 238 increases with increasing governor pressure in the conduit 241 and increasing vehicle speed'and decreases with increasing throttle pressure and throttle opening. Therefore, the line pressure, which is initially supplied to the servo motor 117 yfor the front brake 34 and also to the piston 59 for the front clutch 32 for engaging these friction devices when the selector valve piston 242 is in its D2 position, increases wit-h accelerator opening and decreases with increasing Vvehicle speed. The line pressure is made to increase with increased accelerator opening so that the front clutch 32 and the front brake 34 have the capacity to take the additional 36' torque from the vehicle engine which results from depression of the accelerator 192 and opening of the engine throttle. `As -has been hereinbefore explained, ther hydraulic torque converter 31 is of the'usual type providing a decreased torque multiplication as the speed 40 increases; and, therefore, line pressure can be and is decreased with increasing governor pressure and vehicle speed `since the engaging devices in the gearing behind the torque converter 31 needl t-ake a decreasing torque with the decreasing torque multiplication of the torque converter 31. The line pressure is also suplied to the` servo motor 12S-for the brake 35 and to `the piston 65 for the clutch 33 for engaging these friction devices when the transmission is in low speed 4drive or high speed drive as will be described. The line pressure is made to vary as 4above described, in accordance with throttle opening and vehicle speed, so that the engaging pressures of the friction brakes yand clutches are just a little higher than is required to carry the torque by each of these clutches and brakes as the vehicle speed and enthe torque, the engagement of these friction engaging devices and the consequent completions of the power trains are relatively smooth.

The compensator pressure in the conduit 238 func tions on the low oil pressure regulator'valve 108 to cause an increase in the pressure within 'the torque Vcon- Averter 3-1 as the accelerator is depressed and'to kcause al decreasein the pressure within the torque converter 31 as,V The compensator pressure` -is applied to the lower end of the regulator valve 108 and the vehicle speed increases.

tends to move -the piston 160 upwardly against the action of the spring 164 so as to increase the metering eiect between the land 162 and the lower edge of the port 168, thereby lrelieving a greater amount of iluid from the torque converter 31 iiowing through the outlet conduit 172 of the torque converter 31. Thus, as the compen- 'sator pressure in the conduit 238 increases, the bleeding eect of the valve. 108 is increased tov decrease the uid pressure in the converter 31; and, as the compensator pressure decreases, this bleeding eiect decreases to cause an increase iny the pressure inthe torque. convener 31. Thus, the pressure in the torque converter 31` is. increased as the vehicle accelerator is moved toward open throttle position, and the pressurev in the torque converter 31 is decreasedY -as the vehicle speed increases. This regulating action of the huid pressure in the torque converter 31 is.. provided, since a greater iuid pressure is requlred in thetorque converter lwith increasing torque output of the vehicle engine, and. a decreasing pressure in t-hetorque converter 31 is sufficient with decreased torque multiplication. by the torque converter with increasing vehicle speeds.

The 2-3 shift valve 112 has the governor pressure. from. the conduitl 241 impressed on it through the branch conduit 286andi the ports 281:'and 278'. The governor pressure, isy effective on. the upper end of the valve piston 2.66 and on the upper surface of the land 267 and tends to move the piston. 266Y and the piston 265y downwardly out of the intermediate speed drive positions of thepistons in which they are illustrated into their high speed` drive positions. This movement of the valve pistons 265 and 266v is opposed` by four different forces, namely; throttle pressure exerted. through` the plug, 254, andV the spring 271, a shift valve plug pressure appliedon the lower Iface of the landV` 267, the force. due to the spring. 270, and the forcedue to line pressure applied to thelower face of the land 273. 'I'fhe throttle pressure isapplied to the lower end of the valve piston 264 through the conduit 215 and the port 274, andy this throttle pressure is effective throughthe spring 271 tending to. oppose movement of the piston 265 downwardly. The spring 270 is. eiective between the landf 267 and a xed part and also tends to hold the piston 265A against suchmovement. Line pressure is, applied from the conduit 288 and I port 28-2 between the lands 272 and 273, andnsince the land 273 is larger than the land 2.72,` the line pressure thus produces a` resultant force onv the piston. 266. oppos' ingV its movement downwardly.v

The plug 264 functionsv as, aV regulator valve to provide the shift valve plugv pressure effective on the land 267. rlhe throttle` pressure in the. conduit 215 applied` to the lower end. of. the plug 264 tendstomove the plugagainst v the action of the spring 271 so as` to open the. port 275y and thereby. supplyfpressure tothe conduit 310I andl theA port 277 of the 2-3 shift valve. The' pressure supplied to the port 277 iiows into the cavity for the valve piston'. 265- and actsv on. the upper end of the plug 264 tending to return the plug. 264. downwardly to a position blocking the port 275. The` plug 264 thus. functions as a` regulating valve, opening the port 275 on anincrease-in throttle pressure and closing the port 275 when the pressure within the conduit 31th and within the cavity yfoi-the piston 265, whichistermed the shiftvalve plug pressure, becomes. sufficient to. augment the force dueto the spring 271.suiiicient`1yv so asto move the plug 24M-down-V wardly., This shift valve plug pressure increaseswith throttle pressure butr is. less than-throttle pressurefbyaf predetermined amount due tothe force provided by, the

,spring 271 onf the. plug 264.v Thisshift-, valve plug pressure inthe cavity for the piston 265 is-app1iedon` the lower yface of. the land-2.67.V and also, iny kaddition-.tov the otherkthree. forces above mentioned, tends to holdthe piston` 265 from movement downwardly into: its: highspeeddriveposition.

When the governorvpressurein the conduit 241, which= isapplied. ontheZ-B shift valve 112` through theports: 281 and 278-, becomes-.suiciently great, so that it over.-V comesthe force on the pistons 265 and 266i ductos-the shiftvalve plug pressure on-the lower faceov the landl. 267the force due tothe spring270, the force due tothe. throttle pressure on.. the plug 264. exerted. through'` the' spring271on the p iston 265 andthe force-duezto--the line.`

pressure applied througnthe port 282; the pistons 264 between. the lands. 26S" and1 269 connectsy the ports 284 and 27.9; Line pressure is. supplied to: the port 284 of the 2 3 shift. valve 112 from-,the conduit 289 and the port 247 of the manual` valve 102, andline pressure thus ows between the lands1268- and 269, the port 279',l and the conduit` 28.7 to.1 the. pistonl 65- for the rear clutch 33 and engagesther rear clutch. 33. The. front clutch. 32 remains engaged, and the high' speed power train is thus com pleted through the transmission.

Thefline pressure in the conduit 287 also flows to the disapply 'cavity 123 of the servo motor 11-7 for the front brake, 34. It is' assumed thatthe' shift from intermediate kspeed. drive; to direct drive is made when the kaccelerator 1,92 isvin'. apartially opened throttle position; and, under thesefconditions; thereis an appreciable throttlel pressure inl the; conduit. 215; Thisv throttle pressure is applied through. the branchV conduit 354cm the upper end of the 3-2 control valve piston 346-, and the piston'346 is thus heldv at the. limit of its movement downwardly against the action of the spring 349' eiective ony the-piston'. Theline pressure in theY conduit 287 thus flows through. thepoit 352- ofthe-valve 113, the groove: betweenl thev lands 347 and 348 of the 3'-2 control valve piston 346, the port 351, the conduity 365 and the'port'362 to thefront servo release' control valver 11:12. The line pressure in the port 362. acts against the front: servo release control? valve piston. 358 and moves. it to the limit. of its movement upwardly so as to connect the. ports. 3625 and' 3611 Line pressure thus hows from the' port' 3621 through the'. port 361i and the conduit 364-` to thedisapply cavity'123' of the-front brake servo motor 1117. The forces' duetov line pressure in the cavity 123. and the' spring 124 tending to'v m'ovethe piston 1:18 to disengaging: position'. overcomeA the force due to line pressure on the other sideY of' the piston 118, andthe piston` 1618 moves to release: the brake. 34'. Thus, the intermediate speed;k power train. is broken, as' the direct' drive power train., is completed..

A downshift" from high speeddrive to intermediate speed drive; may 'be obtained with: the accelerator' 192 released' and with: the vehicle. coasting with decreasing speed to a stop. Under these conditions, the governor pressure' applied tothe upper end of the' 2-3 shift valve 112'. is decreasing: and' the; throttle' pressure' applied to they plug 264'v and the. shift: valvev plug. pressure applied' on the lower facey of. thefland 267? are substantially zero. Eventually, the governor pressure will decrease to the point at.which` thesprings 271 and-270 and the line pressure applied to thelandf 273 are effective so as to move the pistons: 265 and 266 :to the limitI of their movement upwardly into'. the'. intermediate speed:v positions ofthev pistons. The line'pressure at the port 284i in the intermediatev speedz position of the piston 26S' isblocked by thea-Ian'd268', andv theconduit 28.7j and' its port 279, which have fluid pressure' applied to' them for completing the high. speed drive, are drained tothe sump through the port; 28=3,.the conduit',v 2-6'1, the port 2'53 ofthe manual va1ve- 1'021, the groove between the lands- 245@ and 246 and.' thebleed'` port 254.- 'lhe draining of fluid' pressure from the conduit 2861 causes-'the rear' clutch-v 33 to dis'- engage thus hreakin'gsthe high speed'fdrive;

When the throttley pressure is' very low, asI withl the' ltsumpaslh'as been7 previouslil described. 'Ihe'land-Sll of the valve 346 blocks the port 352, and therefore, the fluid from the disapply cavity123 must pass through the restriction 355 which retards its flow and retards the application of the front brake 34 which is due to the presence of line pressure in the apply cavity 122 remaining in this cavity for all operation in the D2 range. The restriction 355 is putin the draining conduit for the disapply c avity 123 under the condition for released accelerator due to the fact that the rapid application of the front brake 34, which would otherwise result, would cause anundue lurch and shock to the vehicle; and the delayed application of the front brake 34 also limits noise,which would result due to the brake 34 being applied before the rear clutch 33 is disengaged. In connection with the 2-3 shift valve piston 265, it should be noted that the land 268 is slightly larger than the land 269; and hence theline pressure that is between the lands 268 and 269, when the groove between these lands connects the ports 284 and 279 for the high speed drive operation, tends 'to hold the piston 265 in its direct drive position. Hence, all other factors being equal, the pistons 265 and 266 will move into their intermediate speed positions at a lower governorl speed than that at which they are shifted into their high speed drive positions, and hunting movement of the pistons 265 and 266 is thus prevented.

A kickdown, that is, a downshift at open throttle position of the accelerator 192, may be had due to the action of the downshift valve 186. Movement of the accelerator 192 to Yan open throttle position and a corresponding movement of the downshift valve piston connects the ports 189 and 190 -by means of the groove between the lands 187 and 188. The port 190 is connected with the line pressure supply conduit 141, and line pressure is thus supplied .through theport 189 and the conduit 28S connected therewith `to a port` 276 of the 2-3 shift valve 112. Assuming that the transmission is in direct drive and the pistons 264, 265 and 266 are in their direct drive positions to the limit of their movement downwardly, the port 276 is open with respect to the land 267; and line pressure from the-port 276 is thus applied onto the lower face of the land 267. This application of line pressure moves the pistons 265 and 266 to the limit of their movement upwardly into their intermediate speed l drive positions, assuming that the vehicle is not travelling at an unduly' high speed at 'which the governor pressure applied to the upper end of the piston 266 would be sufficient to prevent this movement. The shift valve piston265 in its intermediate speed position drains the conduit 287 as previously described so as to disengage the rear clutch 33 and cause engagement of the front brake 34 by a draining of the disapply cavity 123 of the servo motor 117 yfor this brake. Since the throttle pressure under these conditions is high, the 3-2 control valve piston 346 willbe atvthe limit of its movement downwardly; and the disapply cavity 123 of the servol motor 117 is drained through the wide open ports 352 and 351 and the groove betweenV the lands 347 and 348 of the 3-2 control valvepiston 346 rather than through the delay restriction 355. Under high engine torque conditions, a delayrof application of the front brake 34 is neither desired nor required, and immediate engagement of the front brake 34 provides a smooth downshift from direct drive to intermediate drive.

The manual valve 102 in its Dl position so controls the transmission that it will start in -low speed drive and on increasing vehicle speed will shift into intermediate speedy drive and thereafter will subsequently 'shift into highspeed drive. The manual control valve piston 242 in its D1 position connects the same ports with the line pressure supply port 250 as were connected fin the D2 position of the manual valvepiston 242 with the exception that the port 255 is blocked with respect to the port 250 and is drained through the -front lend-of the cavity in,v which the manual valve piston 242 is' disposed. The

release of Huid' pressure in the port V255 causes a corresponding bleeding of iiuid pressure from the lower end of the range control valve 115, Vthe tlow being through the-port 314 and conduit 318 to the port 255. The upper end of the range control valve is connected by means of the port 315 with the governor pressure supply conduit 241, and governor pressure is exerted on the upper end of the range control valve piston 312 moving it to the limit of its movement downwardly so that the ports 315 and 316 are connected. The governor pressure is thus applied through the conduit 319 and the port 298 on the upper endvof the 1-2 shift valve 114.V Prior to such movement, assuming that the valve 102 is put into Dl condition when the vehicle is stationary and the governor pressure is zero, the conduit 319, together with the upper end of the cavity in which the piston 290 is disposed, is drained through the ports 317 and 314 connected whenever line pressure is applied on the lower end of the range control valve piston312 as in the D2 range. The spring 311 underthese conditions moves the 1-2 shift valve piston 290 upwardly into its low speed position and thus assures that the valve piston 290 is in its low speed position when a start is made in the Dl range.

The 1-2 shift valve piston 290, when in its low speed position shifted tothe limit of its movement upwardly, connects the ports 301 and 302 by means of the groove between the lands 293 and 294. The port 301 carries -line pressure from the conduit 308 and port 2490i the manual valve 102, and line pressure is thus supplied to the conduit 330 connected with the port 302. Fluid pressure Hows through the conduit 330 and its restriction 331, the rear servo apply regulator valve 109 and the conduit 332V to the servo motor for engaging the rear brake 35 to complete the low speed forward drive power train.

The function of the 2-1 control valve is to provide at times an unrestricted connection between the conduit 330 and the front servo release cavity 123 of the servo motor 117 for the brake 34 and at other times to effectively connect the cavity 123 in series with the restriction 331 along with the rear servo 125, in the latter condition the cavity 123 and the servo 125 being connected in parallel both ybehind the restriction 331. The piston 333 of the 2-1 control valve is under the control of three forces: namely, that due to throttle pressure which is `applied on the lower end of the piston 333, the force due to the spring 337, and a force due to Huid pressure from the branch conduit 344 applied between the lands 335 and 336 through the port 340. The land 335v is larger than the land 336, and the pressure in the conduit` 344 thus tends to move the piston 333 to the limit of its motion downwardly.

As the fluid pressure in the conduit 330 and in the branch conduit 344 increases on the manual valve piston 242 being movedvinto its Dl position, the piston 333' of the 2-1 control valve 110 will move to the limit of its movement downwardly by reason of the pressure built up in the branch conduit 344 as long fas there is no throttle pressure within the conduit 215. The 2-1 control valve is so arranged that wheneverv there is throttle pressure of any substantial value within the conduit 215, the lpiston 333 is moved thereby to the limit of its movementi upwardly.l Since, generally, in starting the vehicle, when the control valve piston 242 is moved to its Dl positionf the accelerator 192 is released, the 2-1 control valve piston 333 may be assumed to move immediately to the limit of its movement downwardly, the pressure building up in the conduit 344 because the restriction 331'im-pedes the duid ow to the rear servo 125. The 2-1Vcontrol valve piston 333 when it is moved to the limit of its movement upwardly' eeotively connects the conduit 363 connected with the front servo release cavity 123 in series behind the restriction 331 through the branch conduit 345, the port 339, the groove between the lands 334 and 335 and the port 342. On theother lhand,\when the piston 333 isat the limit of its movement downwardly, the restriction 331 is4 by-passed; and the conduit 363 connected with the front servo release cavity 123 is connected ahead of the restriction 3311 throughy the branch conduit 344, the port 338, the groove between, the lands334. and. 335 and the-port 342.

The 2'1 control valve piston 333- functions under the three forces above-mentioned so that the piston at the" limit of its movement downwardly by-passinlg the restriction-331- wheneverk line'` pressure is supplied to the conduit 330 from the l-2r shift valve 1114 for completing the low speed drive, duevtothe pressure building up in'y the conduits 330 and 344, unless there isthrottle pres-A surey existing in the conduit 215; Onthe other hand,- when` the conduit 330 is bled tocomplete the second speed ratio as willY be subsequently described', the 2-lA control valve piston 333 is under Iall conditions of "throttle pressure at the limit ofJ its'movement vupwardly in which the restriction is inseries with the conduit 363 con# nectedy to the 'front servo releasey cavity' 123;Y This is due tothe factrthat when the conduit- 330 is-bled', there is-v no pressure effectivebetween the lands 335 and 336'v overcoming theforce duelto the-spring-337 either alonel or augmented by force on the lower end of the piston 333 due to throttle pressure in the conduit 21'5.

The valve pistons 320 and 321 of' the'rear servo apply regulator valve 109 are initially at the limitof their move-- ment downwardly under the action of thespring 324 thus fully opening the portl 325 with respect to the port 328, andthe initial ilow of iluid pressurel into the conduit 332 and to the servo motor 12S is unrestricted by the valve 109. As the pressure buildsup in the conduit 332 and inthe servo motor 125, the pistons 320 and 3-21 move upwardly assuming that the accelerator 192 is in closed throt- -motor 125 is applied through the port 329" on the lower end'of the piston 320. When the pressure these'rvo; motor 125 reachesv a predetermined low value, the piston' 321Y is moved'` upwardly suiciently so that.v the land' 322 closes the port 325 and prevents further iluid How' into the-conduit-332 and servo motor 125. The valve 109 is responsive to changing position ofthe accelerator due to"l throttle'pressure from the conduit 2'15 which isimqgrressed` on the upper' end of the valve piston 32`1 through the port' 3264 augmenting' ther action of the' spng 3241 in tending tomove'theipistons 321 and'V 320 downward-ly'.` Whe'n'the accelerator 192 is moved to an open throttle position', the throttle pressure'is suicient'so asto hold andniain'-V tain the pistons 320VVV and! 321? at' the limit ofi theirmove` ment downwardly to' un-restrictedly connect the' ports -325I and 323 regardless of buildup ofvuid pressure in 'the' conduit 332 and servo motor 125; however,` at closedv throttle positions of the vaccelerator 192;` thepressure" in the conduit 332 andrinithe'servo motor -1-25 for the rear bralce 35" is regulated' andi maintained at a reduced value bythe valve 109:i Asan example, if ythe line pressure isl 80`-poundsr per square inch; at closed throttle, the rear servo applyl regulatoryalve 1`09`regulatesths pressure inv ahcertain embodiment of the invention to 40 poundsperf square'inch-inrthe conduit' 3321 The` restriction 33-1 in restricting fluid.v ow'and" the rear servo-apply regulator valvec109 with its regulating action function' when the manual` valve-piston 2'42 is rst put into its D1 position' to' provide aisrnooth. and' gradual engagement. ofith'e rearf brake 35"-for"completing thelow speed power train'.

The ii'uidr pressure inthe conduit 330 provided when' the manual v-alve piston 242 is firstV moved into its D1 position ows through branch conduitV 344l and' moves the; pistonV 3-33 of` the 2-1 control valvedownwardly. as: above described. Fluid thenfows' from thebranch con# duit SM1-through the port 338, the groove lbetween the lands 334-.and 335,l the: port 342 and the' conduit-363to the port 359`onf"the upper end o-f-theffront servorelease control-valve 111. This fluid pressure moves the front servorelease'control valve piston 356 downwardly to' the 2'4 limit of its movement toy connect the ports-359' and 360, and the fluid from the port 359 ows into the port 360 and through the conduit 364 to the disapply cavity 123 of the servo motor 117 for the yfront brake 34. Fluid pressure is supplied to the apply cavity 122 of the servo motor 117 as` previously explained from the port 249 of the manual valve 102',v and this application of fluid pressure to the disapply cavity 123 disengages the brake 34 so yas to break the intermediatespeed drive and allow the low speedy drive'to be effective.

In D1 range, as the vehicle speed increases and the governor pressure in the conduit 241 andI connected conduits increase; the increasing governor pressure, applied through the ports 315 and 316 of the range control valve 115, the conduit 319 and the port 298 onthe upper end ofthe 1-2 shift valve 114, tends,` to move the l-2 shift valve piston 290 from its low speed positionin which it is illustrated -to its intermediate speed position which is at thelimit of its movement downwardly. The piston 290 moves frornits low toits intermediate speed posi- Ition against :the action of the spring 311-, and the shift valve plug pressure also opposes this movement of the 1-2 shift valve piston 290. As has been previously explained, the shift valve plug pressure is present in .the ports 27S` and 277 of the 2 3 shift valve 112, and the shift valve plug pressure is transmitted through the conduit 310; the port 305, the'groove between -the lands 291 and 2920i the. piston 290 when it isrin its low speed position, andthe ports 297 and 2961-to the-lower end of the piston 290. When the governor pressure increases sufficiently to overcome the shift valve plug` pressure and the forceV due to the spring 311, the 1-2 shift valve piston 290 moves to the limit of its movement downwardly into its intermediate speed position. In this position, the port 301 carrying line pressure is blocked; `and the port 302, which in the low speed position of the 1-2 shift valve piston290 has line pressure supplied to it, is` drained to the sump through the bleed port' 303 and the groove betweenI thelands 293-and 29'4. The vservo motor' 125 for the rear brake 35 is drained throughrthe conduit 332, theports 328 and325,the conduit 330, the restriction 331 and theport 302. The disapply cavity 123 of the front'brake 34--isv drainedthroughthefconduit 364,- the ,ports` 360 and 359,'thef conduitv 363, the ports 342 and 339, the restriction 331, Ythe conduit 330 and the port 302.- Since the' pressure in the conduits 330 and 344'is relieved for this ratio change, the 2-1 control valve piston 333is'at the limit of its'movement upwardly so as to-block the-port-338'by the land 334 for this ratio change, sothat uid from the port 342drains through `the restriction'331. l Y Y Thus, on-the 1-2'- upshift, the iluidl draining'from'the front-servo-release: cavity 123 and yalso the iuidA draining fromthje rear servo liows through the restriction 331. The front servo release cavity 123 and the rear servo 125 areineifect connected in parallel behind'the restriction 331-g and between-this restriction and the rear servo 125; the-rear' servoapply regulator valve is disposed.v The `front-servo 11-'7 during this shift functions as a pump discharging iluidfthrough` its conduit 364,. andtheV rear servo 125= functions as anv accumulator receiving this uid, althoughtheactu'al pressure of th'e-'uid applied tothe rear servo125 is` reduced by the valve` 109, as# suming that the accelerator is inacl'osed'throttle posi-v tion.- The fron't' servo117 iunct'ionsin thisy manner'as a' pump sincey line pressure-remains applie'dvvithink theA applycavi-ty'122 ofthe front'servo 117. The piston 118 ofthisf servo is moved under suchV application' of line pressure andV dischargesvfluid into its" conduit 364'- faster" than the uid can iiow through'the restriction 331; and, therefore, this uid flows through the branch conduit 345,- the part of the conduit 330" between the restriction 331 and t-heV valve 109, the rear servo regulator valve 109, andtheconduit S32-to the: rear servov125function ing'as an;accumulator.Y Duringthis'shiftyitwillbe apf preciated 'thatthe pumping eifectl'by the front servo 117 and theaccumulat'or electby the rear servo 125 function-to hold the rear brake 35 engaged longer than would otherwise ybethe case to give a greater overlap of -engagement. The pressure of engagement for the rear Abrake 35 should, however, be/lower to correspond with the decreased torque transmitted' from the vehicle engine undcrrelatively closed throttle conditions, and the rear servo apply regulator valve 109 functions -forlthispurpose. VIf the 1-2 upshiftis, however, made with a relatively wide open engine throttle, the rear servo apply regulator valve 109 under the action of the throttlepressure in the conduit' 215 is out of action, that is, moved downwardly so as to unrestrictedly connect the ports 32S' andv325; andthus, under these conditions, the full uid pressure from the front servo 117 is applied to the rearse'rvo 125, and the overlap of engagement by the brakes34 and 35 is in effect shortened. In connection with this shift from first to second speed drive, it should be borne in mind -that the low speed brake band 68 unwraps, that is, it is self-deenergizing for the direction of reaction for low speed driveffrom the drive shaft to the driven shaft. Therefore, thevalve 109 reduces the pressure applied to the rear servo 125 to a less extent than if the band 68 were self-wrapping or self-energizing. It is this wrapping effect of the rear band 68 that must be reckoned with, particularly in making a 2-l shift with released acceleraton' which will be subsequently described. The principal purpose for the rear servo apply regulator `valve 109 is, however, for thepurpose of giving asmooth first to second speed shift, since the pressure of application on the rear servo 125 due to the accumulator effect of the front servo 117 would otherwise be too highunder released accelerator conditions.

' A` subsequent upshift to highvspeed drive is obtained through the action of the 2-3 shift valve 112. This valve is subject to the governor pressure that increases withthe speed of the vehicle, and this valve 112 is moved into its high speed position to complete the high speed drive by action of the increasing governor pressure in the same manner as in the D2 range.

A shift from direct drive to intermediate speed drive with the accelerator released andthe vehicle speed decreasing or when the accelerator is moved to an open throttle kickdown position may be had in the D1 range in the same manner as in D2 range. A downshift from intermediate speed ratio to low speed ratio also takes place in the D1 range on decreasing vehicle speed and governor pressure. VAssuming the transmission is in intermediate speed, When the governorpressure applied to the port 298 of the 1-2 shift valve 114 decreases sufciently, the spring 311 will move the 1-2 shift valve piston upwardly into lits low speed position. It should be noted that when the 1-2 shift valve piston 290 is in its intermediate speed position, its land 292 blocks the port 305 carrying shift valvev plug pressure, and hence the shift valve plug pressure is not effective to augment the action of the spring 311 in returning the 1-2' shift valve piston 290 into its low speed position. The piston 290 thus can be expected to shift at lower governor pressures from its intermediate speed position to its low speed position as compared to a movement in the opposite direction,` thus eliminating hunting of the piston.

When the v1-2 shift valve piston 290 returns to its low, speed position, line pressure is again admitted through port 301, the groove between the lands 293 and 294 and the port 302 to'the conduit 330. This change of drive may be made either under closed throttle con. ditions or -when the accelerator is'in an open throttle position, but usually this shift occurs when the accelerator is relaxedl The pressure flows into the conduit 330 and 'branches off to both the front servo release cavity 123 and also to the rear servo 125. I'he 2-1 control valve piston 333 for a 2-1 shift is at the limit of its movement downwardly under" closed throttleconditions. t There is no throttle pressure in conduit 215 to oppose this movement under the action of the increasing pressure within the branch conduit 344 impressed on the land 335. If the engine throttle is open, on the other hand, throttle pressure in the conduits 215 and 354 is impressed on the lower end of the valve piston 333 and holds the piston at the limit of its movement upwardly. With relaxed throttle, Awith the piston 333 at the limit of movement downwardly, the 2-1 control valve 110 effectively connects the front servo release cavity 123 directly with the branch conduit 344, by-passing the restriction 331. The pressure from the branch conduit 344 ows to the front servo release cav-ity 123 through the port 338, the groove between the lands 334 and 335, the port 342, the conduit 363, the ports 359'and 360 and the conduit 364. Fluid from the conduit 330 ows to thev rear servo through the restriction 331, the valve 109 and the conduit 332. A rapid and unrestricted application of uidpressure thus takes place to the disapply cavity 123 of the front servo 117, but the application of fluid pressure to the rear servo 125 is retarded and decreased by means of the restriction 331 and the rear servo apply regulator valve 109. It should be noted that the rear brake 35, under closed throttle conditions, when the driven shaft 26 tendsto drive the'vehicle engine 29, is wrapping or self-energizing, s'o that this 1-2 shift would be very abrupt and severe V'without a cushioning effect for the rear brake 35. The effect ofthe 2-1 control valve is to feed fluid pressure directly to vthe front servo disapply cavity 123 and to feed the rear servo 125 through the oriiice 331, in addition to th'eregulator valve 109,50 that the front brake 34 is immediately disengaged and the rear servo 125 is allowed to drift into engagement, It-will-be observedthat, previously, for an upshift from rst to second speed ratio, uid pressure released from the front servo release cavity 123 and from the rear servo 125 have been co-ordinated through the single restriction 331 but for a downshift from second to lirst ratio, this 'co-ordination is overruled and the front servo 117 is madevto act prior'to the rear servo 125. l

If a 2-1 downshift is made under open throttle conditions, the 2-l control valve 333 is moved upwardly by the throttle'pressure so as to again connect both the front servo release cavity 123 and the rear servo 125 in parallel with the restriction 331. Under these conditions, the vehicle engine 29 is driving so that the rear brake 35 when itengages does so with an unwrapping effect, and a smooth power train change can be obtained by permitting the pressure to build up simultaneously in the front servo release cavity 123 and on the rear servo 125.

' With the transmission being in intermediate speed drive, the accelerator 192 may be moved to an open throttle kickdown positionin Vorder to obtain low speed drive. 7 When the accelerator is in its kickdown position, line `pressure is applied .t the conduit 285 as previously described, and this line pressure is ltransmitted through the connected ports 276, the conduit 309 and the port 304 tothe 1-2 shift valve 1.14 between the lands v292 and 293. YSince the land 293 is larger than the land 292, the 1-2 shift'valve piston 290 is moved upwardly, `assuming that the vehicle shift valve 290 in its :low speedv posit-ion will again admit line pressure into the conduit 330 through theport 302' for the purpose of applying the rear brake l35 and disapplying the front brake 34. The rear servo apply regulator valve and the 2-'1 control valve in this case, however, will function under a relatively high throttle pressure. The throttle pressure in this case will hold the rear servo apply regulator valve piston 321 over to the limit of its movement downwardly regardless of increases in pres` sure in theconduit 332, and the throttle pressure will hold the 2-1 control valve'piston 333 to the limit of its movement upwardly even when the pressure in the conduits 330 and 344 build up to full line pressure. Thus full line pressure is applied tothe servo motor 125 fo r the rear;`

l2-7 brealeS-S, and the cavity 123 of the servo motor 117 and therearl servov 125. are filled through the restriction 331 whichf'cushions theriunctioningof the brakes 3ft-andv 35. Thus, under theseconditionsfthe engagementl of the front brake34 is relatively retarded to reduce the band overlap to co'rrespondtoI the high torqueY conditions of the vehicle engine existing with-` the accelerator-in an open throttle position.'` e

When-the-manual valve piston A2'42isvm'oved into its L position',` assuming' that this is done while the'vehicle is* at rest?,` the lower speed power train` through the transmission wilil becompl'eted. The manual valve piston 242 in its L position connects the port248'and 249 with theA linelpressure supply port. 250by-means ofthe groove be-V tween 4theslands 243 alud 244'and connects therport-252 withetheL line' pressure'i supply port 25-1, the* latter' being connectedalongwith-the port 250 with the line pressure supplyfconduit's'lll'and 259;- The line pressure supplied to the port'248 and the conduit 256- Aconnectedtherewithv suppliespressure to the front c1utch32 -or engaging it' and alsoL supplies pressure to thev governor valve 116: as previously described-,fand the linepressure supplied toi the port 249 owsthrough the' conduit 258-to the apply cavity 122fo=theservo motor 117 forthe front brake 34 as previously described.-v The linepressure supplied to the port-252 ilows'intothe connected conduits 260' and 307, and the line pressure i'n the conduit' 260 flows therethrough to* therdownshift fvalvef103 while the line pressure in -the conduiti30l `flowsfto the l'-2 shift valve 114. The fluid pressure. within the conduit 260 flows through the yport 1191,1th'e groove'betweenthe lands 187 and-188 of the downshiftfvalv'e piston118f6, the portf189and'the conduit"285rtoyone of the vports"276. Itis assumed that when thefmanualcontrol valve 242 is moved into its L- position; the accelerator is in aliclosed throttle-*position-'so that -the downshift :valve piston connects the ports 191 and189`. The-line pressure inthe last-mentioned portV 276' ows into 'the cavity for theV piston' 265,the1plug.- 264' atthis time' being held at the limit of its-movement downwardly by the spring 271, and thisfline pressure acts'on the flower face of the Aland 267 andholds the-pistons 265 and 2`66=^of the 2f-"2nV shift valve 1112'atthe lmit- Of their movement upwardly'in they downshifted position of the valve 112i 'I'his'linepressure also owsinto Vthe-'lowerhport 276fand1through the conduit 309: and the port 30`4between theY lands 292 and 293`and tends to move and hold the I-2 shi-ftvalve piston- 290 upwardly in` itsdownshifted orl low; speed drive position, since the `latter landsA are unbalanced; TheV line pressure in the conduit 307-flovvs` to the p`o1t`299` of the 1- 2 shift Valve114iand is impressed on'- vthe 'lower' face' ofthe nland 295 and provides` an' additional force von the 1-2 shift valvev piston holdingfthis pistonfinfitsflow'V speed position. Since bo'tho'f` the shittV valves` 112-and 1`1`4 arein'their downshifted positions; the f' transmission is in'its low' speed ratio, the connecf tions'tottheclutches andbrakes-from the line pressure conduit" 141 being'as previously described;

- `If?the.manualivalvefpiston^242is moved into its L positioxrfromi either its"` D2 or D1 position' While the vehicleiswtravellingf, the" transmission will be shifted from` its-higher speed Tratios'to itslow speed ratiozand 'will thenr remain :ini its low speed drive; Iflth'ervehicle-is travellingV its'highfspeed i ratio, .the transmission will .iirst down-- shift to`l intermediate speed ratio 'and then'lfinally to? low spee'd` ratio'andwillfremain in thelatterfratio; The vlinev pressure'suppliedto the port 276"of-the;2`-3:shift valve* willlfact'fonithei lowerface' ofthe land 267 and'fwill move the`2`3shi-ft valve pi'storrf26'5to1its-downshifted posi'- tonj. assuming-that th'e'vehicle speed is" not toohigh: They lineV pressure supplied to`the"port-7 304 of the l'2vshiftv val-ve i114iwilf1`tend5tomove the shiftvalvef290 to'its` downshifted position and"wi1l do" so when "thevehicle: speed dropsi suiciently; The po'rtf299"of"the 1 2 shifty valve114'iis -.blockedirfthei intermediate speeddive position'offthe'piston290g` however; oncefthepiston 290 moves'- 28 into its lowspeed position, the-pert-299is opened and applies linel pressure on'thelowcr face of the `land 295 which holdsVA the piston-.290 in-itsflow speedidrive position regardless of any-increases in vehicle speed.

Reverse drive inthe transmission is made operative by moving the manual selector valvepiston 242 into its R position. In this "position, the groove between the lands- 244v and 245 connects-:the'line pressure supply port 250 with the port 249 and the conduits 258 Yand 308. The conduit 258v isconnected with the apply cavity 122 of the front brake 34;-however,the frontbrake 3'4 remains disapplied as will nowbe explained. y The line pressure supplied to the conduit-308 -ows to the port 301 of the 1-2 shift valve 1.14, through the groove between theY lands 293 and 294`of4the l-Zshiftvalve piston 290 and into the conduit 3130.: As has been previously explained, line pressure in the conduit'3i30Y is transmittedto the servo motor y125 for theV rear brake 35 through the rear servo apply regulator valve 109 so asto engage therear brake 35, and the line pressure from the' conduit 330 -is'transmitted through the Z-l controlvalve 110 and the front servo release control valve 111to the'releasen cavity 123 of the servo motor117 for the front brake 34, so that the front brake remains disengaged;`

The manual selector valvepiston 242 connectsthe line pressure supply port 251 with the ports 252 and 253. Pressurefrom the port 252, as-hasbeen described in connection with the drive in low range is transmitted through the downshift valve 103v andconduits-ZSS and 309' to the 2-3 shift valve 112 and the 1-2shift valve 114-for holding these valves in their downshifted positions, and line pressure from the port 252v is alsotransmitted through the conduit 307` aspreviously described to the port 299 of the l-2 shift valvegfor applying line pressure on the land 295 also tending to hold theshiftvalve 290 in `itsdownshifted position'. Theli-ne pressure supplied to theportl 253flows through the connected conduit 1261-to the port 283 of the- 2-3` shift valve and'als'oto the port 21'4` ofthe throttle modulator valve-1061 Sincerthe-ZSshift valvepiston- 265 is inY its downshiftedv posit-ion,..the1ine pressure ows from the port 283` =through the'V groove between the lands 2687an'd 269, the port 279 and thev conduit 287%tothe rear clutch piston'f65.- Therear' clutch isthen engaged; andv Y it,v inI conjunction with the rear band v35 .Which-:is also enthrottle pressure isfthusV suppliediundiminishedtofthe portsf 212: and.' 213 and-'thereby respectivelyv through the.

conduits: 240 'and 239--to the"port`s"'231'r a'nd 230' of the compensatorY valve: 105. The' compensator valvef 105 thus hasiagreaterithrottle pressure elect' on-.it than for the-'rforwar'd drives, so; that the compensator."va1ve'105, reduces'theiA compensator 'pressure' inf-the compensatorcom duit 238tto-:ra greater extent'with openingofthe engine throttle-than is-the-case forrth'efforward drives;V The comfl pensatori:` pressure as: hasA been: previously, mentioned is` eiiectiveron-the regulatorfvalvesr-l? and 108, and-the"V net result-.of the* decreasedf'compensator pressurefisan increaseiin thelinefpressurefin theconduit 141 regulated by thek valvef107 and` an increasein theconverter pressure'y in thefconverter: 31--regnlated1byf the. valve108'.-` The increased? linepressure is necessary: in reverse drive in orderv that ythe brake 35- maya-have suiici'ent` holding-ability to take th'erincreasedfreaction on it for this drive.-

Y As-f: hasbeens. previously described,- linev pressure v is:

thronghitherco'nduitsi257 and 288-and the 'port 282 be'- 

